The present invention relates to a semiconductor device and a method of manufacturing the semiconductor device. For example, the invention can be preferably applied to a nonvolatile memory having FINFET.
In recent years, dimensions of a metal insulator semiconductor field effect transistor (MISFET), which is a component of a large scale integration (LSI) using silicon, have been reduced. In particular, gate length of a gate electrode is steadily decreasing. Along with such a reduction in size of MISFET, it has been difficult to suppress a short channel effect and to maintain current driving force together. FINFET, which is one of such novel structural devices, is intended to increase the current driving force by using a side surface of a FIN (active region) as a channel.
On the other hand, one type of nonvolatile memory includes a memory cell configured of a split gate cell using a metal-oxide-nitride-oxide-semiconductor (MONOS) film. This memory cell is configured of two MISFETs, i.e., a control transistor having a control gate electrode and a memory transistor having a memory gate electrode. Such transistors can also be improved in memory characteristics by using the FIN structure. In addition, a NAND flush memory can also be improved in memory characteristics by using the FIN structure in a memory transistor.
Tzu-Hsuan Hsu, et al. “A High-Speed BE-SONOS NAND Flash Utilizing the Field-Enhancement Effect of FinFET” IEEE 2007 p. 913-916 mentions that in a NAND flush memory, electric charges are injected into a top portion of a fin and then also injected into the side portion of the fin. In particular, it is mentioned that in FN write, the writing speed is fast in the early stage of 1 μs or less and then slowed.